Degassing of slag coated melt

ABSTRACT

There is disclosed a degassing process and degassing apparatus incorporating a slag-breaker which instead of being an integral welded unit is formed of several parts which are readily stored and readily transported and are secured together by fasteners at the site of use. The slag-breaker includes a tapered member in the form of a conical receptacle and a top for this member. The slag-breaker is assembled near the degassing vessel, the top being secured substantially below the rim of the member. The slag-breaker is secured to the gas entrance or snorkel of the vessel with the rim of the tapered member above the opening in the snorkel.

United States atet [191 Cashdollar, Sr.

[ DEGASSING OF SLAG COATED MELT [76] Inventor: Robert E. Cashdollar,Sr., R.D. N0.

7, Butler, Pa.

[22] Filed: May 17, 1972 21 Appl. No.: 254,162

[57] ABSTRACT There is disclosed a degassing process and degassingapparatus incorporating a slag-breaker which instead of being anintegral welded unit is formed of several parts which are readily storedand readily transported and are secured together by fasteners at thesite of use. The slag-breaker includes a tapered member in the form of aconical receptacle and a top for this member. The slag-breaker isassembled near the degassing vessel, the top being secured substantiallybelow the rim of the member. The slag-breaker is secured to the gasentrance or snorkel of the vessel with the rim of the tapered memberabove the opening in the snorkel.

6 Claims, 6 Drawing Figures PATENIEDUEB 4 I975 sum 1 or 2 PRIOR ARTFIG.5

PATENTEDUEC 41975 SHEEIZM 2 FIGA DEGASSING OF SLAG COATED MELTBACKGROUND OF THE INVENTION This invention relates to the making ofsteel and has particular relationship to the degassing of the melt inthe making of steel. The degassing is a purification step which isintroduced in the making of certain grades of steel particularly by thebasic-oxygen process. In continuous casting the degassing precedes thepouring of the steel into the chill mold of the casting line.

In the degassing step the snorkel or gas-entranceopening of a degassingvessel is injected into the melt in a ladle. The ladel and vessel aremoved vertically, one relative to the other, as the vessel is exhausted.The gas from the melt flows through the vessel and out through theexhaust openings. The vessel is composed of metal, lined internally withrefractory brick. Typically, the cost of relining a vessel may be ashigh as $120,000.00.

The surface of the melt is coated with slag and the penetration of theslag into the degassing vessel to any substantial extent results inrapid deterioration of the refractory brick and demands relining of thevessel. A slag-breaker is provided to reduce the penetration of the slaginto the vessel.

In accordance with the teachings of the prior art the slag-breaker is anintegral welded conical unit of steel in the form of a closed receptaclewhich is mounted over the mouth or opening of the snorkel with a guidingshell extending from its top into the opening. Typically, theslag-breaker is a cone having a diameter of about four feet and a heightor altitude of about one and onehalf feet. The prior-art slag-breakerincludes a rod or bar which extends laterally from the conical member.This bar is engaged by wires to secure the slag-breaker to the outersurface of the snorkel. The breaker extends part way across the end ofthe snorkel and IMOWOOL sealing material or the like is interposedbetween the breaker and the end. When the snorkel first penetrates intothe melt the slag-breaker deflects the slag away from the snorkelreducing the absorption of slag into the opening of the snorkel. Theslag-breaker is fused into the melt but it is contemplated that thelateral walls of the snorkel prevent the slag from penetrating into theopening in the snorkel after the slag-breaker is fused.

Because of its awkward structure, the prior-art slagbreaker is notreadily stored or shipped. It is readily damaged during shipment orwhile in storage. Its movement from one place to another is costlybecause, not only does it occupy a large volume on the shipping vehicle,but it also must be moved by hand to and from the vehicle. In addition,in use it leaves much to be desired in reducing the flow of slag intothe opening in the snorkel.

SUMMARY OF THE INVENTION This invention arises from the realization thatthe prior-art slag-breakers are not satisfactorily effective in reducingthe flow of slag into the degassing vessel because they are held bymeans of the rods against the end of the snorkel in a position exposinga substantial part of the end of the snorkel to the slag as the snorkelenters the melt. The slag moves along the end penetrating between thesealing material and the end and wearing a filet in the end around theopening. As the filet becomes larger, in repeated use of the vessel,more and more slag penetrates through the opening in the snorkel intothe vessel ultimately requiring replacement of the refractory brick.

It has been discovered that this undesirable functioning of theslag-breaker can be eliminated by eliminating the suspension rods and atthe same time the transporting and warehousing difiiculties and the highshipping cost which the prior-an slag-breakers impose are alsoameliorated. In addition, the cost of making the slagbreaker ismaterially reduced.

In accordance with this invention the slag-breaker, instead of being anintegrated welded unit, is composed of separate parts; a tapered memberin the form of a receptacle and a top. The rods are dispensed with.Instead, the rim of the tapered member extends above the outer end ofthe snorkel and is directly secured to the outer wall of the snorkel.The rim of the tapered member thus extends above the entrance opening inthe snorkel and the penetration of slag into this opening is sharplyreduced. The parts according to this invention are shipped andwarehoused separately and when used are removed to the site of thedegassing vessel and bolted together near the degassing vessel beforebeing mounted on the snorkel. The tapered parts when separate may benested so that a large number may be shipped and warehoused inrelatively small spaces. These parts need not be moved manually; theycan be moved by a hoist or fork-lift. The cost of welding the top to thetapered member is eliminated.

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of thisinvention, both as to its organization and as to its method ofoperation, together with additional objects and advantages thereof,reference is made to the following description, taken in connection withthe accompanying drawings, in which:

FIG. 1 is a view partly in side elevation and partly in section showingdegassing apparatus in accordance with this invention;

FIG. 2 is a view in section showing a slag-breaker, in accordance withthis invention, as it is integrated into degassing apparatus;

FIG. 3 is a view in side elevation showing how tapered members of aslag-breaker in accordance with this invention are transported andstored;

FIG. 4 is a view in side elevation showing how the tops of slag-breakersin accordance with this invention are transported and stored;

FIG. 5 is a fragmental view partly in section showing in detail themanner in which a slag-breaker in accordance with this invention ismounted on the snorkel; and

FIG. 6 is a fragmental view partly in section showing in detail how aslag-breaker in accordance with the teachings of the prior art ismounted on a snorkel and how such slag-breaker operates in deflectingthe slag.

DETAILED DESCRIPTION OF INVENTION nected. The vessel 11 also includes asnorkel 27 having by means of which the slag-breaker is secured insealing relationship with the opening 29. Only two such diametralopenings 49 and wires 51 are shown but there may be more than twosuspensions, typically four spaced 90 around the member 41.

The tapered member 41 and top 43 are secured together by fasteners 53.Each fastener 53 includes a bolt 55 which passes through the member 41and top at an angle and is secured by a nut 57 or Dzus or other kindredfastener. The bolthead firmly engages a washer 59 spanning internallythe tapered member and the end of the plate 45. The top 43 is secured asubstantial distance below the upper rim 61 of the member 41. While onlytwo diametral fasteners 53 are shown, there may be more than two suchfasteners 53, for example, four spaced 90 around the vessel 41.

During transportation or in storage the tapered members 41 may be nestedon a pallet 63, as shown in FIG. 3, and the tops 43 may be stacked on apallet 65, as shown in FIG. 4. A large number of slag-breaker parts maybe handled in this way.

In use the slag-breaker 13, with the parts 41 and 43 secured together bythe fastener 53, is mounted on the snorkel 27 by the wire 51. An annularstrip 67 of sealing material, such as KAOWOOL, is compressed between theplate 45 and the end of the snorkel 27. The ladle 17 is placed on theplatform and the hydraulic drive (not shown) of the platform isenergized to raise the ladle 17 so that the snorkel 27 with the slagbreaker 13 on its end penetrates into the melt 19. The slagbreaker 13deflects the slag 21. Since the rim 61 of the member 41 is above theopening 29, the slag is prevented from penetrating under the end of thesnorkel 27 when the snorkel 27 first enters the melt 19. Theslag-breaker 13 melts, but the outer wall of the snorkel keeps the slag21 away from the opening 29 and minimizes the flow of slag into theopening 29 and the formation of a filet on the inner corner 69 of thesnorkel. The hydraulic drive (not shown) moves the melt 19 upwardly anddownwardly relative to the snorkel 27 and the degassing proceeds.

In the prior-art structure of the slag-breaker 71 (FIG. 6) the wire 73engages rods 75 to hold the plate 77 in compressing relationship withthe sealing material 67. But a substantial portion 79 of the end of thesnorkel 27 extends beyond the slag-breaker 71. As the snorkel 27 andslag-breaker 71 move into the melt 19, the slag 81 under the end 79penetrates through the sealing material 67 producing ever growing filet83.

While a preferred embodiment and practice of this invention has beendisclosed herein, many modifications thereof are feasible. Thisinvention is not to be re stricted except insofar as is necessitated bythe spirit of the prior art.

I Claim:

1. In the degassing, with a degassing vessel during the making of steel,of a melt over whose surface a layer of slag extends, the said vesselhaving an entranceopening means including an opening through which saidmelt including the gas therein flows into the degassing vessel, themethod of minimizing the slag from said layer which penetrates into saidvessel through said opening means, which comprises providing a taperedmember in the shape of a receptacle having a hollow surface and taperingfrom a cross-sectional region of larger area to a cross-sectional regionof substantially smaller area, providing, separately, a top for saidmember, said top including a plate and a shell extending from saidplate, said members being readily nested and said tops being readilystacked, securing said top and member to said opening means with saidtop secured to the inner surface of said member and said shell extendinginto said entrance opening and with the tapered surface of said memberextending into said melt with said region of larger cross-sectional areaoutwardly of said melt, so as to deflect the slag away from said openingmeans, said plate and the portion of said receptacle from the region ofsmaller area to the region where the plate is secured defining a closedvolume, and interposing sealing material in the region bounded by saiden'- trance means, the surface of said plate outwardly of said volume,and the outer surface of said shell.

2. A slag-breaker including a generally tapered member in the form of areceptacle tapering from a region of small cross-sectional area to arim, a separable top for said tapered member, said top including a platehaving a shell extending from said plate fastener means securing saidtop to the inner surface of said tapered member, said top being securedto the inner surface of said tapered member a substantial distanceinwardly of the rim of said tapered member, said plate and the portionof said receptacle between said plate and said region of smallcross-sectional area defining a closed volume, said shell extending fromsaid plate outwardly of said volume, said member being provided alongits rim with openings for securing the breaker to entranceopening meansof a degassing vessel.

3. Liquid metal treating apparatus including a deg assing vessel fordegassing a melt over whose surface slag extends, said degassing vesselhaving entrance-opening means having entrance-opening means for entranceof said melt, a slag-breaker including a generally tapered member in theform of a receptacle and tapering from a rim to a termination ofsubstantially smaller crosssectional area than said rim and a separabletop for said member including a plate and a shell extending from saidplate, fastener means for securing said top internally to said membera-substantial distance inwardly of the rim, said plate and the portionof said member between said plate and said termination of smallercrosssectional area defining a closed volume, and said shell extendingfrom said plate outwardly of said volume, means securing saidslag-breaker to said entrance opening means so that the part of saidmember between the top and the rim extends over said opening of saidentrance-opening means so as to substantially reduce the penetration ofsaid slag into said vessel and said shell extends into saidentrance-opening means, and sealing material interposed in the regionbounded by said entrance-opening means, the portion of said plateoutwardly of said shell and the outer surface of said shell.

4. The combination of claim 3 wherein the slagbreaker securing meansincludes suspensions connected directly to the member and to theentranceopening means.

5. The method of claim 1, for carrying out a plurality of degassingoperations, in whose practice, preparatory to their successive assemblyfor a degassing operation, a plurality of the members are nested and aplurality of tops for the respective members are stacked.

6. In the degassing, with a degassing vessel during the making of steel,of melts over each of whose surfaces a layer of slag extends, the saidvessel having an entrance-opening means with an opening through whicheach melt including the gas therein flows into the degassing vessel, themethod of minimizing the slag from said layers which penetrates intosaid vessel through said opening; the said method comprising providing aplurality of tapered members of generally conical form having externalsurfaces lending themselves readily to nesting, each said member havingopenings near its rim for suspending said last-named member, providing aplurality of tops for said members, each top including a plate fromwhich a shell extends, said tops lending themselves readily to stacking,preparatory to the use of said members for minimizing said slagpenetration, nesting a plurality of said tapered members and stacking acorresponding plurality of said tops, preparatory to the degassing of amelt, securing a said top to a corresponding said member internally ofsaid last-named member with the shell of said last-named top away fromthe apex of said last-named member and the said openings of saidlast-named member rim-ward of the last-named top, and by means ofsuspensions engaging said last-named openings, suspending saidlast-named member from said entrance-opening means, with said last-namedshell penetrating into said opening of said opening means and withsealing material in the region defined by said opening means outwardlyof said opening, the portion of said top outwardly of said shell and thecontiguous external surface of said shell.

1. In the degassing, with a degassing vessel during the making of steel,of a melt over whose surface a layer of slag extends, the said vesselhaving an entrance-opening means including an opening through which saidmelt including the gas therein flows into the degassing vessel, themethod of minimizing the slag from said layer which penetrates into saidvessel through said opening means, which comprises providing a taperedmember in the shape of a receptacle having a hollow surface and taperingfrom a crosssectional region of larger area to a cross-sectional regionof substantially smaller area, providing, separately, a top for saidmember, said top including a plate and a shell extending from saidplate, said members being readily nested and said tops being readilystacked, securing said top and member to said opening means with saidtop secured to the inner surface of said member and said shell extendinginto said entrance opening and with the tapered surface of said memberextending into said melt with said region of larger cross-sectional areaoutwardly of said melt, so as to deflect the slag away from said openingmeans, said plate and the portion of said receptacle from the region ofsmaller area to the region where the plate is secured defining a closedvolume, and interposing sealing material in the region bounded by saidentrance means, the surface of said plate outwardly of said volume, andthe outer surface of said shell.
 2. A slag-breaker including a generallytapered member in the form of a receptacle tapering from a region ofsmall cross-sectional area to a rim, a separable top for said taperedmember, said top including a plate having a shell extending from saidplate fastener means securing said top to the inner surface of saidtapered member, said top being secured to the inner surface of saidtapered member a substantial distance inwardly of the rim of saidtapered member, said plate and the portion of said receptacle betweensaid plate and said region of small cross-sectional area defining aclosed volume, said shell extending from said plate outwardly of saidvolume, said member being provided along its rim with openings forsecuring the breaker to entrance-opening means of a degassing vessel. 3.Liquid metal treating apparatus including a degassing vessel fordegassing a melt over whose surface slag extends, said degassing vesselhaving entrance-opening means having entrance-opening means for entranceof said melt, a slag-breaker including a generally tapered member in theform of a receptacle and tapering from a rim to a termination ofsubstantially smaller cross-sectional area than said rim and a separabletop for said member including a plate and a shell extending from saidplate, fastener means for securing said top internally to said member asubstantial distance inwardly of the rim, said plate and the portion ofsaid member between said plate and said termination of smallercross-sectional area defining a closed volume, and said shell extendingfrom said plate outwardly of said volume, means securing saidslag-breaker to said entrance opening means so that the part of saidmember between the top and the rim extends over said opening of saidentrance-opening means so as to substantially reduce the penetration ofsaid slag into said vessel and said shell extends into saidentrance-opening means, and sealing material interposed in the regionbounded by said entrance-opening means, the portion of said plateoutwardly of said shell and the outer surface of said shell.
 4. Thecombination of claim 3 wherein the slag-breaker securing means includessuspensions connected directly to the member and to the entrance-openingmeans.
 5. The method of claim 1, for carrying out a plurality ofdegassing operations, in whose practice, preparatory to their successiveassembly for a degassing operation, a plurality of the members arenested and a plurality of tops for the respective members are stacked.6. In the degassing, with a degassing vessel during the making of steel,of melts over each of whose surfaces a layer of slag extends, the saidvessel having an entrance-opening means with an opening through whicheach melt including the gas therein flows into the degassing vessel, themethod of minimizing the slag from said layers which penetrates intosaid vessel through said opening; the said method comprising providing aplurality of tapered members of generally conical form having externalsurfaces lending themselves readily to nesting, each said member havingopenings near its rim for suspending said last-named member, providing aplurality of tops for said members, each top including a plate fromwhich a shell extends, said tops lending themselves readily to stacking,preparatory to the use of said members for minimizing said slagpenetration, nesting a plurality of said tapered members and stacking acorresponding plurality of said tops, preparatory to the degassinG of amelt, securing a said top to a corresponding said member internally ofsaid last-named member with the shell of said last-named top away fromthe apex of said last-named member and the said openings of saidlast-named member rim-ward of the last-named top, and by means ofsuspensions engaging said last-named openings, suspending saidlast-named member from said entrance-opening means, with said last-namedshell penetrating into said opening of said opening means and withsealing material in the region defined by said opening means outwardlyof said opening, the portion of said top outwardly of said shell and thecontiguous external surface of said shell.